Summary
Many of the issues discussed become a matter of preference but there is an important area of applications where the use of resettable PTCs is becoming a requirement. Much of the design work for personal computers and peripheral devices is strongly influenced by the Microsoft and Intel System Design Guide which states that “Using a fuse that must be replaced each time an overcurrent condition occurs is unacceptable.” And the SCSI (Small Computer Systems Interface) Standard for this large market includes a statement that “....a positive temperature coefficient device must be used instead of a fuse, to limit the maximum amount of current sourced”.

The PTC / fuse discussion provides some insight as to when PTCs may be the appropriate choice for providing overcurrent circuit protection. The intention is to provide some guidance in choosing the best overcurrent circuit protection device...PTCor fuse...for the application.